Dating volcanic ash and pumice stones from volcano El Misti, Peru, by thermoluminescence

El Misti is one of active volcanos in Peru, and known because it is located close to an important city of Arequipa, at about 17 km. There has been in the past several eruptions and the volcano is covered with lava, ash, etc. from such eruptions. The edifice is composed of a stratotocone called Misti 1, two stratocones designated Misti 2 and Misti 3 and a summit cone Misti 4. In this work samples from Misti 3 have been collected for TL dating. In the past charcol has been used for radiocarbon measurements and found age varying from 25000 to 35000 years. The TL dating produces ages between 28700 and 32300 years

Thermoluminescence and defect centers in synthetic diopside

MgCaSi2O6 polycrystal was synthesized by the devitrification method. The dosimetric characteristics by TL of this prepared polycrystal was investigated. This material exhibits TL peaks at 115, 160, 210, 260 and 280 °C. The dosimetric peak occurs at 260 °C with a well defined glow curve structure. This peak shows a linear dose response. Electron paramagnetic resonance (EPR) studies have been carried out to identify the defect centers responsible for the TL peaks. Two defect centers in the region of g = 2.0 are found. One of the centers (center I) with a g factor equal to 2.0085 is identified as O− -ion and relates with the observed high temperature 250 and 300 °C TL peaks. Additional defect centers with g = 2.0012 (center II) and 1.982 (center III) are due to F+- centers (electron trapped at an oxygen vacancy). Center II and III correlate with the TL peaks at 160 °C and 106 °C, respectively.Campus Arequip

Dating stalagmite from Caverna do Diabo (Devil'S Cave) by TL and EPR techniques

A cylindrical fragment of stalagmite from Caverna do Diabo, State of Sao Paulo, Brazil, has been studied and dated by thermoluminescence and electron paramagnetic resonance techniques. The thermoluminescence glow curves of stalagmite samples and subsequently gamma irradiated, have shown rise of three peaks at 135, 180 and 265 degrees C. From electron paramagnetic resonance spectra of stalagmite was possible to clearly identify three paramagnetic centers in the g = 2.0 region: Centers I, II and III are due to, CO3- and CO33-, respectively. The additive method was applied to calculate the accumulated dose using thermoluminescence peak at 265 degrees C and the electron paramagnetic resonance signal at g = 1.9973 of CO2- radical. The ages of the different slices of stalagmite were determined from the D-ac-values and D-an-value, obtaining an average of 86410 for central slice, 53421 for second slice, 31490 for third slice and 46390 years B.P. for the central region of upper end.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ Sao Paulo, Inst Fis, Rua Matao,187 Cidade Univ, BR-05508090 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Rua Doutor Carvalho de Mendonca 144, BR-11070100 Santos, SP, BrazilIPEN CNEN SP, Inst Pesquisas Energet & Nucl, Av Prof Lineu Prestes,2242 Cidade Univ, BR-05508000 Sao Paulo, SP, BrazilUniv Nacl San Agustin, Fac Ciencias Nat & Formales, Escuela Profes Fis, Av Independencia S-N, Arequipa, PeruUniv Sao Paulo, Escola Politecn, Dept Engn Met & Mat, Av Prof Mello Moraes 2463, BR-05508030 Sao Paulo, SP, BrazilDepartamento de Ciências do Mar, Universidade Federal de São Paulo, Rua Doutor Carvalho de Mendonça, 144, 11070-100 Santos, SP, BrazilFAPESP: 2014/03085-0CAPES: BEX-9612130Web of Scienc

Mechanisms of TL for production of the 230 degrees C peak in natural sodalite

The thermoluminescence (TL) peak in natural sodalite near 230 degrees C which appears only after submitted to thermal treatments and to gamma irradiation has been studied in parallel with electron paramagnetic resonance (EPR) spectrum appearing under the same procedure This study revealed a full correlation between the 230 degrees C TL peak and the eleven hyperfine lines from EPR spectrum In both case the centers disappear at the same temperature and are restored after gamma irradiation A complete model for the 230 C TL peak is presented and discussed In addition to the correlation and TL model specific characteristics of the TL peaks are described (C) 2010 Elsevier B V All rights reservedFundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP[2007/08008-0]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Thermoluminescence in Lapis Lazuli crystal: Glow peaks and their connection with F-centers estimated by ESR analysis

The mineral Lapis Lazuli exhibits three thermoluminescence (TL) peaks approximately at 140, 260 and 370 degrees C. The TL intensity of the three peaks grows with radiation dose and it saturates only beyond 9 kGy. Electron Spin Resonance (ESR) studies have been carried out to identify the defect centers responsible for the thermoluminescence peaks. The ESR spectrum of the as-received natural sample presented the typical six signals due to Mn2+ ion and a large signal around g = 2.030 due to Fe3+ ion. Room temperature ESR spectrum of irradiated Lapis Lazuli shows the formation of a defect center. This center (center I) is identified as an F-center (singly ionized oxygen vacancy) and seems to correlate with 140 and 250 degrees C TL peaks. An additional defect center is observed during thermal annealing experiments and this center (center II - assigned to F+-center) appears to originate from an F-center (oxygen vacancy with two electrons). This F-center, precursor of center II, may be related to the observed high temperature 360 degrees C TL peak in Lapis Lazuli.FAPESPCAPESUniv São Paulo, Inst Fis, Rua Matao, BR-05508090 São Paulo, SP, BrazilUniv Fed São Paulo, Inst Mar, Rua Doutor Carvalho Mendonca 144, BR-11070100 Santos, SP, BrazilUniv Nacl San Agustin, Escuela Profes Fis, Fac Ciencias Nat & Formales, Arequipa, PeruUniv Fed São Paulo, Inst Mar, Rua Doutor Carvalho Mendonca 144, BR-11070100 Santos, SP, BrazilFAPESP: 2014/03085-0CAPES: BEX-9612130Web of Scienc

Thermoluminescence and optical absorption properties of glass from natural diopside and of synthetic diopside glass

Glasses based on natural mineral diopside and synthetic glasses starting from Oxides of magnesium, calcium and silicon, and some of these glasses doped with 0.1, 1.0, 2.0 and 4.0% of Ag, have been produced for the study of their thermoluminescence and optical absorption properties. A marked different behavior is observed in various glasses, including glass with silver nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.FAPESPCAPESUniv Sao Paulo, Inst Fis, Rua Matao,Travessa R 187, BR-05508090 Sao Paulo, SP, BrazilUniv Sao Paulo, Dept Engn Met & Mat, Escola Politecn, Av Prof Melo Moraes 2463, BR-05508900 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, Rua Doutor Carvalho de Mendonca 144, BR-11070100 Santos, SP, BrazilUniv Natl San Agustin, Escuela Profes Fis, Fac Ciencias Nat & Formales, Av Independencia S-N, Arequipa, PeruUniv Fed Sao Paulo, Dept Ciencias Mar, Rua Doutor Carvalho de Mendonca 144, BR-11070100 Santos, SP, BrazilFAPESP: 2014/ 03085-0CAPES: BEX-9612130Web of Scienc

Dating stalagmite from Caverna do Diabo (Devil´S Cave) by TL and EPR techniques

ABSTRACT A cylindrical fragment of stalagmite from Caverna do Diabo, State of São Paulo, Brazil, has been studied and dated by thermoluminescence and electron paramagnetic resonance techniques. The thermoluminescence glow curves of stalagmite samples and subsequently gamma irradiated, have shown rise of three peaks at 135, 180 and 265 °C. From electron paramagnetic resonance spectra of stalagmite was possible to clearly identify three paramagnetic centers in the g = 2.0 region: Centers I, II and III are due to , and , respectively. The additive method was applied to calculate the accumulated dose using thermoluminescence peak at 265 °C and the electron paramagnetic resonance signal at g = 1.9973 of CO- 2 radical. The ages of the different slices of stalagmite were determined from the Dac- values and Dan- value, obtaining an average of 86410 for central slice, 53421 for second slice, 31490 for third slice and 46390 years B.P. for the central region of upper end